Despite new leadership in the United States promising to cap the country's greenhouse gas emissions, some environmental leaders say it is unlikely that an international climate treaty will pass in the next year. During his campaign, US president-elect Barack Obama supported a global cap-and-trade agreement for regulating his nation's carbon emissions. As a result, many international observers are hoping the United States will agree to binding emissions-reduction targets at the high-profile climate change negotiations scheduled for December 2009 in Copenhagen, Denmark. Such optimism may be unrealistic, however. The ongoing financial crisis, a potential withdrawal of U.S. troops from Iraq, and an increasingly unstable war in Afghanistan will likely dominate the White House's political agenda in 2009.

If the United States does not accept mandatory emissions-reduction targets at Copenhagen, a panel of environmental leaders and climate negotiators said last week that the climate conference will be much less meaningful.

'I doubt U.S. legislation will be ready by Copenhagen,' said Elliot Diringer, vice president of international strategies at the Pew Center on Global Climate Change and a deputy assistant to former President Bill Clinton. 'The odds of accomplishing comprehensive negotiations at Copenhagen are not very high. In fact, they're very low.'

The outcome from Copenhagen will hinge in part on how quickly the U.S. Congress can pass a cap-and-trade bill, and on whether lawmakers would approve an international climate treaty before adopting domestic legislation. In 1997, when the Congress was last faced with a similar timing challenge, the U.S. Senate rejected the Kyoto Protocol in a 95-0 vote before the international treaty was even finalized.

'We cannot repeat the mistakes of the past - first working out an international climate negotiation and then returning to U.S. legislation,' said Robert Orr, the United Nations Assistant Secretary-General for Policy Planning. 'It won't work.'

Some of the panel's negotiators remain optimistic. Thomas Becker, chief climate negotiator for Denmark, said the financial aid package that the U.S. Congress swiftly passed in October is an indication that climate change legislation could be approved in the next year. 'An aid package was passed overnight. It shows if the political will is there, you can do it,' Becker said. 'It's not impossible. It's a question of priority.'

Quick passage of an international agreement is a challenging prospect because of the lawmaking rules of the U.S. Senate. To ratify a treaty, the legislation would require support from two-thirds of the Senate, or at least 67 votes. In comparison, only a majority in both chambers is necessary to pass a bill, and a bill requires just 60 votes to avoid a filibuster - a legislative tool that delays a vote by indefinitely extending the time for debate.

Congressional Democrats failed to pass an emissions cap-and-trade bill earlier this year. But the incoming Congress, which includes 20 more Democrats in the House of Representatives and 6-8 new Democrats in the Senate, is expected to face less partisan opposition in the next two years. In addition, current members of Congress have recently suggested more willingness to address climate change.

Some Congressmen, however, are already attempting to control expectations. Jeff Bingaman, chair of the Senate Energy Committee, suggested last week that a cap-and-trade bill may not be ready until 2010. 'The reality is, it may take more than the first year to get it all done,' he said, according to an Associated Press report.

Aside from capping emissions, the Obama administration is expected to act quickly on a variety of other significant climate-related measures.

Obama has suggested he would grant the state of California permission to regulate carbon dioxide emissions from automobiles under the U.S. Clean Air Act, which the Bush administration has opposed since December. The reversal would allow California, and the 16 states that have followed its lead, to cut vehicle emissions 30 percent between 2009 and 2016.